The present invention relates generally to endoscopes for use in observation of a body cavity in a human body, an interior of a machine and the like, and more particularly, to an improved inserting portion of the endoscope.
In general, an endoscope for observing a body cavity or a coelom in a human body comprises an operating body. The operating body is provided therein with an insertion opening for a forceps. An eyepiece barrel and one or more manipulating dials are mounted to the operating body. An inserting portion extends from the operating body, and is composed of a flexible section and a bendable section capable of being curved in at least one plane. A tip component is provided at a forward end of the bendable section remote from the operating body. The tip component is formed therein with a viewing window which is optically connected to the eyepiece barrel by an image-transmitting system. The tip component is further provided therein with a forceps opening which communicates with the forceps insertion opening in the operating body through a forceps channel. At least one pair of manipulating wires have their respective one ends fixedly connected to a shaft section of the manipulating dial which extends into the operating body. The manipulating wires extend through the inserting portion, and the other ends of the respective manipulating wires are fixedly connected to the tip component.
In use of the endoscope constructed as above, the inserting portion together with the tip component is inserted into, for example, the body cavity to be viewed. The manipulating dial is angularly moved about its axis to pull one of the pair of manipulating wires and to loosen the other manipulating wire. This causes the bendable section to be curved, thereby enabling the tip component to be oriented to a desirable direction. Thus, an observer can view any desirable part within the body cavity.
Various bendable sections for inserting portions of endoscopes of the kind referred to above are known from, for example, Japanese Utility Model Application Laid-Open Nos. 55-11250, 57-157302 and 60-190301. The known bendable section is composed of a plurality of tubular members arranged in coaxial relation to each other. Each pair of adjacent tubular members are pivotally connected to each other. At least one pair of tubular wire guides are mounted to an inner peripheral surface of each of the tubular members such that the pair of manipulating wires extend respectively through the pair of wire guides. When one of the pair of manipulating wires is pulled and the other manipulating wire is loosened in the manner described above, each pair of adjacent tubular members are pivotally moved relatively to each other so that the bendable section is curved as a whole.
It is difficult for the conventional bendable section, however, to fix each pair of wire guides to their respective positions on a corresponding one of the tubular members in a correct and accurate manner. By this reason, there may be a case where the wire guides mounted to one of each pair of adjacent tubular members are out of axial alignment with the respective wire guides on the other tubular member. Such misalignment causes an increase in frictional resistance between the manipulating wires and the inner peripheral surfaces of the respective wire guides when the manipulating wires are operated by the manipulating dial. The increase in frictional resistance deteriorates the operability of the manipulating dial, or causes tearing-up of the manipulating wires.
Another bendable sections are also known from Japanese Utility Model Publication Nos. 57-8801 and 58-46801, and Japanese Utility Model Application Laid-Open No. 60-187702. In the known bendable section, each pair of adjacent tubular members are pivotally connected to each other through a pair of pivots. Each pivot has an end portion thereof which projects radially inwardly from the inner peripheral surface of the tubular member. The projecting end portion of the pivot is formed therein with a guide bore. The pair of manipulating wires extend respectively through the guide bores in the pair of pivots associated with each tubular member. It is possible for the the bendable section constructed as above to improve the accuracy in alignment between the guide bores in the pivots associated with one of each pair of adjacent tubular members and the guide bores in the pivots associated with the other tubular member, because the pivots are beforehand determined in their respective positions.
Since, however, the respective end portions of the pair of pivots associated with each tubular member projects radially inwardly from the inner peripheral surface of the tubular member, the interior space of the tubular member is reduced correspondingly, thereby limiting or restricting the size of component parts accommodated in the tubular member so as to extend therethrough.